I find my preferred user name is already taken from time to time when I register on a website, but have never came across someone actively using it. It's always a little disappointing because I want the simplicity of the same username everywhere, but no such luck for me. I usually have to modify it a bit to get something that works.
Whenever I encounter another "mime", I always wonder "are they actually a mime, too? Do I know them?" Not that we all know each other, but over the years I was part of a group that worked with many other mimes, and trained countless performers from several countries and feel like it's just a two degrees of separation kind of thing.
As for my real name, I'm aware of only 1 other person in my country (US) with it. A marathon runner. Not aware of any others in the world. Similar for my DH, but it was funny when his name came up in a television show. It was used as the name of a mutual friend of the characters on the show who were gossiping about something or other. Kinda funny to hear his name pop up!